MEASUREMENT OF GLOMERULAR-FILTRATION RATE IN ICU PATIENTS USING TC-99M-DTPA AND INULIN

Improved and reliable methods for assessing glomerular filtration rate (GFR) in intensive care patients are needed in light of known deficiencies using creatinine clearance. We compared simultaneous two-hour clearances of inulin (C(In)), creatinine (C(Cr)), and Tc-99m-diethylenetriaminepentaacetic acid (C(DTPA)) in 18 medical or surgical intensive care patients (range, 49 to 92 years old) with blood urea nitrogen (BUN) levels >17.9 mmol/liter (0.5 mg/ml), serum creatinine levels >150-mu-mol/liter (0.02 mg/ml). or estimated Cockcroft clearance <60 ml/min. Patients had severe renal dysfunction with average GFR of 35 ml/min (range. 2 to 69 ml/min). C(DTPA) and C(Cr) correlated significantly with C(In), although C(DTPA) tended to provide a closer approximation. Cockcroft clearance (32 +/- 4 ml/min) was grossly similar to C(DTPA) and C(In) and correlated significantly. especially when weight was calculated using actual as opposed to ideal body weight. In a subset of 13 patients with C(In) <30 ml/min. only C(DTPA) was significantly correlated with C(In). In patients in the intensive care unit, C(DTPA) provides a rapid. accurate. and inexpensive clinical assessment of GFR, even at very low GFRs.